Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 3: Fluid dynamics I

DY 3.7: Talk

Monday, March 26, 2012, 11:30–11:45, MA 144

Development of Surface Waviness during Pulsed Electron Beam Treatment — •Renate Fetzer, Wladimir An, Georg Mueller, and Alfons Weisenburger — Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

Pulsed high-current electron beams have shown their capability to improve surface properties such as hardness, wear, or corrosion resistance of metals and alloys without affecting the bulk material. The interaction of the electron beam with a metal target leads to rapid heating and cooling of the surface layer, accompanied by different phase transitions between the solid, liquid, vapor, and plasma phase. As a consequence of the treatment, however, a topographical pattern evolves on the target surface and is conserved upon re-solidification. This waviness can reach typical amplitudes in the range of tens of micrometers, which is disadvantageous for some applications.

In this work, we present a systematic study on the development of surface waviness during pulsed high-current electron beam irradiation, including time- and space-resolved diagnostics during treatment and target analysis after treatment. The experimental studies are accompanied by heat conduction simulations. Possible mechanisms of waviness evolution such as cratering due to substrate inhomogeneity and various hydrodynamic instabilities are discussed.